1. Field of the Invention
The present invention concerns benzoyl peroxide quaternary ammonium lipophilic salicylate based pharmaceutical and cosmetic compositions and their use especially in treatment of acne.
The etiopathology of acne, although unclear, starts in formation of a characteristic lesion: the comedo. This produces a blockage in the pilosebaceous canal following dyskeratinization of the infundibular zone of the canal. A major effect of the blockage is to modify the rheology of the sebum and the physicochemical properties of the area. Such modification allows resident cutaneous strains to hyperproliferate which in turn triggers an inflammation reaction in the organism.
Benzoyl peroxide has been known for several years to be a particularly interesting keratolytic agent among recognized therapeutic acne treatments. In addition, it has good bacteriostatic properties.
Use of standard antibiotics in acne treatment is also widespread. They do, in fact, shown considerable bacteriostatic and anti-inflammatory activity. Orally administered active antibiotics are numerous. Among these, clindamycin and especially erythromycin show topical activity.
Antibiotics have previously been combined with benzoyl peroxide in order to increase the activity of topical antiacne compositions. In particular, erythromycin has already been combined with benzoyl peroxide (French patent FR 77 021 57).
However, a major drawback of the use of antibiotics (either alone or in combination with benzoyl peroxide) lies in their prolonged use whereupon bacterial flora become resistant, rendering the antibiotics less effective in subsequent treatment (LEYDEN, J.J; J. Am. Acad. Dermatol. 8 (1) 41-45 (1983)).
Further, benzoyl peroxide-erythromycin combinations are unstable over periods of time.
Quaternary ammonium compounds (M. GLOOR, Arch. Dermatol. Res. 265 207-212 (1979)) have been envisaged as replacements for antibiotics in topical treatment of acne. It has been shown that certain quaternary ammonium compounds are as effective as antibiotics against the main strains responsible for acne, without inducing resistance.
Combining benzoyl peroxide with quaternary ammonium compounds for topical treatment is also known (French patent FR 73 29 233). In such compositions, benzoyl peroxide acts by decomposing to liberate active oxygen in situ.